When performing a distillation, first the condenser is filled with cold running water. Next, heat is applied to the mixture which is to be distilled. The mixture is heated until it boils, and the hot vapors will travel up to the distillation head. Measuring the temperature of the vapors helps us to identify the liquid being distilled, and will help to confirm its purity. If the vapors are pure, they will have a constant temperature, equal to the boiling point of the liquid being distilled. As the vapors travel into the condenser, they will be cooled and will liquify. The liquid droplets (called the distillate) run down the condenser and are collected in a receiving flask. A liquid can be easily separated from nonvolatile contaminants by using a Simple distillation apparatus, such as this one. Since the nonvolatile components in the distillation flask will not evaporate, the vapors (and the resulting condensate) will be pure.